This invention relates to new and improved latching formation for molded containers and cartons. More particularly it relates to beak type locks of improved form which are stronger than prior structures.
In the past, the carton designers of molded cartons have produced cartons with beak type locks. However, such prior designs and constructions have relatively weak engaging surfaces and are subject to rupture and failure when opening is attempted. In some instances the beak fails and in other instances the orifice wall ruptures. The problem of failure and rupture was ever present in prior constructions. Although, over the years, many good designers attempted to produce improved locks, failures and ruptures still occurred and the problem was not completely solved.
Examples of prior designs appear in the U.S. Pat. Nos. to Alsman, 3,217,963; Friday, 3,245,600; Hartman, 3,276,656; and Seest et al, 3,471,078. In each of these prior designs, developed over the years, and with practical experience, the orifice engaging surface remained simple, Seest et al attempted to reinforce their beak with a horizontal rib at the very top thereof away from the latch engaging surface. It was not obvious to any of the prior workers in the field to provide a horizontal peripheral rib at the engaging surface or a vertical rib extending upwardly therefrom.
The molded containers and cartons on which the latching formation in accordance with the instant invention is useful include egg cartons, food containers such as boxes for sandwiches, chicken parts, pizzas, and hamburgers in fast food operations, and other food articles and other items.